1. Technical Field
The present invention relates to the technical field of an electrooptic device such as a liquid crystal device and an electronic device, such as a liquid crystal projector, having the electrooptic device.
2. Related Art
Liquid crystal devices, one of this type of electrooptic device, are frequently used not only for direct-view displays but also for the light modulators (light valves) of, for example, projection display devices. Particularly for projection display devices, strong light from the light source enters the liquid-crystal light valve. Therefore, to prevent the thin-film transistors (TFTs) in the liquid-crystal light valve from increasing in leakage current and malfunctions due to the light, a light-shielding film serving as means for blocking off the incident light is built in the liquid-crystal light valve. For such light-shielding means or light-shielding film, for example, Japanese Patent No. 3356429 discloses a technique for improving the function of shielding TFTs using, of the gate lines higher than the semiconductor layer of the TFTs, the part disposed in a contact hole for connecting the gate lines to a back light-shielding film disposed lower the semiconductor layer.
However, in the technique disclosed in Japanese Patent No. 3356429, the contact hole for connecting the gate lines to the back light-shielding film is rectangular along the data lines in plan view. Therefore, this technique has the technical problem that, as the line width is decreased with an increase in the open area ratio required for this type of electrooptic device, it becomes difficult to provide a sufficient area for the contact hole, resulting in an increase in contact resistance.
This type of electrooptic device is of an active matrix type having, on its substrate, pixel electrodes, and scanning lines, data lines, and TFTs serving as pixel switching elements for selectively driving the pixel electrodes. The electrooptic device may have capacitor elements between the TFTs and pixel electrodes to achieve high contrast. The foregoing components are disposed on the substrate at high density to increase the pixel open area ratio and reduce the device size.
Here, it is desirable that the capacitor elements have the highest possible capacitance; but on the other hand, it is desirable that the pixel open area ratio be not traded off. Accordingly, JP-A-2005-115104 discloses a technique for increasing the capacitance of the capacitor elements while maintaining a high open area ratio by forming the capacitor elements on the bottom and sides of the substrate.
The capacitor elements may be used also for shielding the TFTs by using the electrodes which are components of the capacitor elements. For example, JP-A-2005-115104 discloses a technique for reducing the incident light on the semiconductor layer using the capacitor elements.
However, the technique disclosed in JP-A-2005-115104 has the technical problem of complicating the process of manufacture because the recesses for the capacitor elements must be formed by another process different from the process of forming the other components on the substrate. The technique further has the technical problem that the increase in the open area ratio and the decrease in the device size make it more difficult to provide a sufficient area for capacitor elements.